What is the reason for using the Equalizer gains block inside the Frequency Domain Equalizer subsystem in the IEEE 802.11a WLAN PHY demo in the Communications Blockset?

I do not understand the frequency domain equalizer block in the wlan80211a.mdl model.

Answer 1

[MathWorks Support Team]

The Frequency Domain Equalizer block performs a channel inversion on its input data. It generates a set of channel estimates in the WLAN 80211 Frequency Equalizer block by calculating 'H(f) = Y(f)./X(f)', where H(f) is the frequency response of the channel, Y(f) is the frequency response of the channel-corrupted data, and X(f) is the frequency response of the training data that has not been corrupted by the channel.

Once the channel estimate is found, the equalizer gains are found according to:

EG = inv(H(f)) = H*(f) / |H(f)|2

In this expression, EG represents the equalizer gains, inv(H(f)) is the inverse of the frequency response, and |H(f)|2 = H(f) * H*(f). The equalizer simply multiplies the data by the inverse of the frequency response.